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Ch. 5 - Complex Numbers, Polar Coordinates and Parametric Equations
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601당신이 사용하는 게 아니라요?교과서 변경
5장, 문제 5.RE.65

In Exercises 64–70, graph each polar equation. Be sure to test for symmetry. r = 2 + 2 sin θ

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Identify the given polar equation: \(r = 2 + 2 \sin \theta\).
Recall that \(r\) represents the radius (distance from the origin) and \(\theta\) is the angle measured from the positive x-axis in polar coordinates.
Test for symmetry by checking the following: - Symmetry about the polar axis (x-axis): Replace \(\theta\) with \(-\theta\) and see if the equation remains unchanged. - Symmetry about the line \(\theta = \frac{\pi}{2}\) (y-axis): Replace \(\theta\) with \(\pi - \theta\). - Symmetry about the pole (origin): Replace \(r\) with \(-r\) and \(\theta\) with \(\theta + \pi\).
Create a table of values by choosing several values of \(\theta\) (for example, \(0\), \(\frac{\pi}{6}\), \(\frac{\pi}{4}\), \(\frac{\pi}{2}\), etc.) and calculate the corresponding \(r\) values using the equation \(r = 2 + 2 \sin \theta\).
Plot the points \((r, \theta)\) on polar graph paper or using a graphing tool, then connect the points smoothly to visualize the curve. Observe the shape and symmetry based on your earlier tests.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Polar Coordinates and Equations

Polar coordinates represent points in a plane using a radius and an angle (r, θ) instead of Cartesian coordinates (x, y). A polar equation expresses the radius r as a function of the angle θ, allowing the graph to be plotted by calculating r for various θ values.
추천 영상:
05:32
Intro to Polar Coordinates

Graphing Polar Equations

To graph a polar equation like r = 2 + 2 sin θ, calculate r for multiple θ values between 0 and 2π, then plot the points in polar form. Connecting these points reveals the shape, which often corresponds to known curves such as limacons or cardioids.
추천 영상:
3:47
Introduction to Common Polar Equations

Symmetry in Polar Graphs

Testing for symmetry helps simplify graphing and understanding polar curves. Common symmetries include symmetry about the polar axis (θ = 0), the line θ = π/2, and the pole (origin). Checking if replacing θ with -θ, π - θ, or θ + π yields the same equation indicates these symmetries.
추천 영상:
3:19
Cardioids